It will generate WDAT table [1] customized for TCO watchdog.
This allows Windows guests (Windows Server 2008/Vista+) to
use TCO watchdog using built-in generic driver, which
aleviates need to install vendor specific drivers.
Given that enabling it might change guest behaviour
(both Windows/Linux) the feature is disabled by default.
Users that need it can enable the feature with
following CLI option.
-machine 'acpi-watchdog=on'
1)
"Hardware Watchdog Timers Design Specification"
https://uefi.org/acpi 'Watchdog Action Table (WDAT)'
Signed-off-by: Igor Mammedov <[email protected]>
---
include/hw/acpi/wdat-ich9.h | 15 +++++++
hw/acpi/meson.build | 3 +-
hw/acpi/wdat-ich9-stub.c | 15 +++++++
hw/acpi/wdat-ich9.c | 87 +++++++++++++++++++++++++++++++++++++
hw/i386/acpi-build.c | 12 +++++
5 files changed, 131 insertions(+), 1 deletion(-)
create mode 100644 include/hw/acpi/wdat-ich9.h
create mode 100644 hw/acpi/wdat-ich9-stub.c
create mode 100644 hw/acpi/wdat-ich9.c
diff --git a/include/hw/acpi/wdat-ich9.h b/include/hw/acpi/wdat-ich9.h
new file mode 100644
index 0000000000..60a2a6a112
--- /dev/null
+++ b/include/hw/acpi/wdat-ich9.h
@@ -0,0 +1,15 @@
+/*
+ * Copyright Red Hat, Inc. 2026
+ * Author(s): Igor Mammedov <[email protected]>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#ifndef QEMU_HW_ACPI_WDAT_ICH9_H
+#define QEMU_HW_ACPI_WDAT_ICH9_H
+
+#include "hw/acpi/aml-build.h"
+
+void build_ich9_wdat(GArray *table_data, BIOSLinker *linker, const char
*oem_id,
+ const char *oem_table_id, uint64_t tco_base);
+
+#endif /* QEMU_HW_ACPI_WDAT_ICH9_H */
diff --git a/hw/acpi/meson.build b/hw/acpi/meson.build
index 56b5d1ec96..ba974b2f0f 100644
--- a/hw/acpi/meson.build
+++ b/hw/acpi/meson.build
@@ -24,7 +24,7 @@ acpi_ss.add(when: 'CONFIG_ACPI_PCI_BRIDGE', if_true:
files('pci-bridge.c'))
acpi_ss.add(when: 'CONFIG_ACPI_PCIHP', if_true: files('pcihp.c'))
acpi_ss.add(when: 'CONFIG_ACPI_PCIHP', if_false:
files('acpi-pci-hotplug-stub.c'))
acpi_ss.add(when: 'CONFIG_ACPI_VIOT', if_true: files('viot.c'))
-acpi_ss.add(when: 'CONFIG_ACPI_ICH9', if_true: files('ich9.c', 'ich9_tco.c',
'ich9_timer.c'))
+acpi_ss.add(when: 'CONFIG_ACPI_ICH9', if_true: files('ich9.c', 'ich9_tco.c',
'ich9_timer.c', 'wdat-ich9.c'))
acpi_ss.add(when: 'CONFIG_ACPI_ERST', if_true: files('erst.c'))
acpi_ss.add(when: 'CONFIG_IPMI', if_true: files('ipmi.c'), if_false:
files('ipmi-stub.c'))
acpi_ss.add(when: 'CONFIG_PC', if_false: files('acpi-x86-stub.c'))
@@ -33,6 +33,7 @@ if have_tpm
endif
system_ss.add(when: 'CONFIG_ACPI', if_false: files('acpi-stub.c',
'aml-build-stub.c', 'ghes-stub.c', 'acpi_interface.c'))
system_ss.add(when: 'CONFIG_ACPI_PCI_BRIDGE', if_false:
files('pci-bridge-stub.c'))
+system_ss.add(when: 'CONFIG_ACPI_ICH9', if_false: files('wdat-ich9-stub.c'))
system_ss.add_all(when: 'CONFIG_ACPI', if_true: acpi_ss)
system_ss.add(when: 'CONFIG_GHES_CPER', if_true: files('ghes_cper.c'))
system_ss.add(when: 'CONFIG_GHES_CPER', if_false: files('ghes_cper_stub.c'))
diff --git a/hw/acpi/wdat-ich9-stub.c b/hw/acpi/wdat-ich9-stub.c
new file mode 100644
index 0000000000..7c30ef3558
--- /dev/null
+++ b/hw/acpi/wdat-ich9-stub.c
@@ -0,0 +1,15 @@
+/*
+ * Copyright Red Hat, Inc. 2026
+ * Author(s): Igor Mammedov <[email protected]>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "hw/acpi/wdat-ich9.h"
+
+void build_ich9_wdat(GArray *table_data, BIOSLinker *linker, const char
*oem_id,
+ const char *oem_table_id, uint64_t tco_base)
+{
+ g_assert_not_reached();
+}
diff --git a/hw/acpi/wdat-ich9.c b/hw/acpi/wdat-ich9.c
new file mode 100644
index 0000000000..b1930dc71d
--- /dev/null
+++ b/hw/acpi/wdat-ich9.c
@@ -0,0 +1,87 @@
+/*
+ * TCO Watchdog Action Table (WDAT)
+ *
+ * Copyright Red Hat, Inc. 2026
+ * Author(s): Igor Mammedov <[email protected]>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "hw/acpi/wdat.h"
+#include "hw/acpi/wdat-ich9.h"
+#include "hw/southbridge/ich9.h"
+
+#define TCO_REG(base, reg_offset, reg_width) { .space_id = AML_AS_SYSTEM_IO, \
+ .address = base + reg_offset, .bit_width = reg_width, \
+ .access_width = AML_WORD_ACC, };
+
+/*
+ * "Hardware Watchdog Timers Design Specification"
+ * https://uefi.org/acpi 'Watchdog Action Table (WDAT)'
+ *
+ * ICH9 specific implementation.
+ */
+void build_ich9_wdat(GArray *table_data, BIOSLinker *linker, const char
*oem_id,
+ const char *oem_table_id, uint64_t tco_base)
+{
+ AcpiTable table = { .sig = "WDAT", .rev = 1, .oem_id = oem_id,
+ .oem_table_id = oem_table_id };
+ struct AcpiGenericAddress tco_rld = TCO_REG(tco_base, 0x0, 16);
+ struct AcpiGenericAddress tco2_sts = TCO_REG(tco_base, 0x6, 16);
+ struct AcpiGenericAddress tco1_cnt = TCO_REG(tco_base, 0x8, 16);
+ struct AcpiGenericAddress tco_tmr = TCO_REG(tco_base, 0x12, 16);
+
+ acpi_table_begin(&table, table_data);
+ build_append_int_noprefix(table_data, 0x20, 4); /* Watchdog Header Length
*/
+ build_append_int_noprefix(table_data, 0xff, 2); /* PCI Segment */
+ build_append_int_noprefix(table_data, 0xff, 1); /* PCI Bus Number */
+ build_append_int_noprefix(table_data, 0xff, 1); /* PCI Device Number */
+ build_append_int_noprefix(table_data, 0xff, 1); /* PCI Function Number */
+ build_append_int_noprefix(table_data, 0, 3); /* Reserved */
+ build_append_int_noprefix(table_data, 0x258, 4);/* Timer Period, ms */
+ build_append_int_noprefix(table_data, 0x3ff, 4);/* Maximum Count */
+ build_append_int_noprefix(table_data, 0x4, 4); /* Minimum Count */
+ /*
+ * WATCHDOG_ENABLED & WATCHDOG_STOPPED_IN_SLEEP_STATE
+ */
+ build_append_int_noprefix(table_data, 0x81, 1); /* Watchdog Flags */
+ build_append_int_noprefix(table_data, 0, 3); /* Reserved */
+ /*
+ * watchdog instruction entries
+ */
+ build_append_int_noprefix(table_data, 10, 4);
+ /* Action table */
+ build_append_wdat_ins(table_data, WDAT_ACTION_RESET,
+ WDAT_INS_WRITE_VALUE,
+ tco_rld, 0x1, 0x1ff);
+ build_append_wdat_ins(table_data, WDAT_ACTION_QUERY_RUNNING_STATE,
+ WDAT_INS_READ_VALUE,
+ tco1_cnt, 0x0, 0x800);
+ build_append_wdat_ins(table_data, WDAT_ACTION_SET_RUNNING_STATE,
+ WDAT_INS_WRITE_VALUE | WDAT_INS_PRESERVE_REGISTER,
+ tco1_cnt, 0, 0x800);
+ build_append_wdat_ins(table_data, WDAT_ACTION_QUERY_STOPPED_STATE,
+ WDAT_INS_READ_VALUE,
+ tco1_cnt, 0x800, 0x800);
+ build_append_wdat_ins(table_data, WDAT_ACTION_SET_STOPPED_STATE,
+ WDAT_INS_WRITE_VALUE | WDAT_INS_PRESERVE_REGISTER,
+ tco1_cnt, 0x800, 0x800);
+ build_append_wdat_ins(table_data, WDAT_ACTION_SET_COUNTDOWN_PERIOD,
+ WDAT_INS_WRITE_COUNTDOWN,
+ tco_tmr, 0x0, 0x3FF);
+ build_append_wdat_ins(table_data, WDAT_ACTION_QUERY_COUNTDOWN_PERIOD,
+ WDAT_INS_READ_COUNTDOWN,
+ tco_tmr, 0x0, 0x3FF);
+ build_append_wdat_ins(table_data, WDAT_ACTION_QUERY_WATCHDOG_STATUS,
+ WDAT_INS_READ_VALUE,
+ tco2_sts, 0x2, 0x2);
+ build_append_wdat_ins(table_data, WDAT_ACTION_SET_WATCHDOG_STATUS,
+ WDAT_INS_WRITE_VALUE | WDAT_INS_PRESERVE_REGISTER,
+ tco2_sts, 0x2, 0x2);
+ build_append_wdat_ins(table_data, WDAT_ACTION_SET_WATCHDOG_STATUS,
+ WDAT_INS_WRITE_VALUE | WDAT_INS_PRESERVE_REGISTER,
+ tco2_sts, 0x4, 0x4);
+
+ acpi_table_end(linker, &table);
+}
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 19c62362e3..abb3e936fd 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -77,6 +77,7 @@
#include "hw/acpi/hmat.h"
#include "hw/acpi/viot.h"
+#include "hw/acpi/wdat-ich9.h"
#include CONFIG_DEVICES
@@ -109,6 +110,7 @@ typedef struct AcpiPmInfo {
uint16_t cpu_hp_io_base;
uint16_t pcihp_io_base;
uint16_t pcihp_io_len;
+ uint64_t tco_io_base;
} AcpiPmInfo;
typedef struct AcpiMiscInfo {
@@ -203,6 +205,7 @@ static void acpi_get_pm_info(MachineState *machine,
AcpiPmInfo *pm)
pm->pcihp_io_len = 0;
pm->smi_on_cpuhp = false;
pm->smi_on_cpu_unplug = false;
+ pm->tco_io_base = 0;
assert(obj);
init_common_fadt_data(machine, obj, &pm->fadt);
@@ -224,6 +227,8 @@ static void acpi_get_pm_info(MachineState *machine,
AcpiPmInfo *pm)
!!(smi_features & BIT_ULL(ICH9_LPC_SMI_F_CPU_HOTPLUG_BIT));
pm->smi_on_cpu_unplug =
!!(smi_features & BIT_ULL(ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT));
+ pm->tco_io_base = object_property_get_uint(obj,
ACPI_PM_PROP_PM_IO_BASE,
+ NULL) + ICH9_PMIO_TCO_RLD;
}
pm->pcihp_io_base =
object_property_get_uint(obj, ACPI_PCIHP_IO_BASE_PROP, NULL);
@@ -2079,6 +2084,13 @@ void acpi_build(AcpiBuildTables *tables, MachineState
*machine)
acpi_add_table(table_offsets, tables_blob);
build_waet(tables_blob, tables->linker, x86ms->oem_id,
x86ms->oem_table_id);
+ if (machine->acpi_watchdog) {
+ g_assert(pm.tco_io_base);
+ acpi_add_table(table_offsets, tables_blob);
+ build_ich9_wdat(tables_blob, tables->linker, x86ms->oem_id,
+ x86ms->oem_table_id, pm.tco_io_base);
+ }
+
/* Add tables supplied by user (if any) */
for (u = acpi_table_first(); u; u = acpi_table_next(u)) {
unsigned len = acpi_table_len(u);
--
2.47.3
